AP Photo/Chris O'MearaIBM CEO Virginia Rometty attended the Masters on Sunday, but the issue of her Augusta National membership remains uncertain.

Rometty, sitting in a lawn chair, had a prime location just a few rows behind the 18th green. She is known to be an avid scuba diver, not much of a golfer. But she knew enough about the game to applaud several good shots into the final hole.

Rometty has brought the issue of female members at Augusta National back to the fore since being named IBM's new chief executive earlier this year. IBM is one of the longtime sponsors of the tournament, and its last four CEOs, all males, were invited to be members. Augusta National's chairman, Billy Payne, has refused to provide a substantive answer to that question, saying the club's membership decisions are private.

IBM has also declined to comment, and security around the company's hospitality cabin at Augusta was tight all week.

The issue of female members at Augusta was a hot-button issue in 2002, when Martha Burk, then the chair of the National Council of Women's Organizations, campaigned for Augusta National to end its all-male membership and threatened to boycott companies whose executives belonged to the club. Hootie Johnson, Payne's predecessor, responded by cutting loose corporate backers and the Masters was televised without commercials for the next two years.

A planned protest before the 2003 Masters was a dud and the issue slowly receded.

When Payne replaced Johnson as chairman of the club and of the Masters tournament in 2006, he said there was "no specific timetable" for admitting women. The question was raised at the 2007 and 2010 Masters. Both times, Payne rebuffed questions, repeating the club's policy on privacy relating to membership issues.

Because the secrecy level at Augusta National is so high, there could already be a female member that nobody knows about. Though members are visible during the Masters because of their iconic green jackets, not every member was in attendance this week.